ON THE PILOBOLID^E. 
185 
are filled with homogeneous epiplasm (Fig. 6). When this 
preliminary marshalling is completed the bounding lines of 
granules widen, and then a transfer of the granules takes 
place comparatively suddenly ; they pass from the sides of the 
meshes into the intervening spaces, falling together, as it 
were, from all sides to form little roundish or oval balls of 
granules, separated by a network of homogeneous substance. 
Each mass of granules then surrounds itself by a cellulose 
membrane, the granules are dissolved, and we have, according 
to the species, round or ellipsoidal homogeneous yellowish 
spores, embedded in a substance of a gelatinous nature, 
which is perfectly colourless, and binds the whole mass of 
spores together. This interstitial substance has an important 
role to play, as we shall see, in the economy of Pilobolus. 
Since writing the paragraph just given, I have met with a 
description of the formation of the spores of Pytliium and 
Achlya, by Marshall Ward, which bears striking testimony to 
the affinity of those genera to the Mucorini. In that author’s 
description of the formation of zoospores in the sporangia of 
Achlya polyandrcfi the identical phenomenon which I have 
just referred to, of the preliminary marshalling of the granules 
in a network, is repeated. In Achlya apiculctta f we have 
the same occurrence of a network of granules, followed 
suddenly by the production of a granular grey uniform mass; 
a vacuole or clear space then develops, probably in the centre 
of each original mesh, and the lines of division of the zoospores 
are formed. He also seems to attribute exactly the same 
process to the formation of the zoospores of Pythium proli- 
ferum.% These phenomena are also described by De Bary as 
occurring in the formation of the spores of Protomyces.§ 
The spores are arranged, for the most part, in regular 
layers, so that in an absolutely perfect sporange there would 
be a number of concentric shells, each composed of a single 
layer of spores, and the spores in each layer would be placed 
side by side, like cannon balls at a government arsenal. It is 
difficult to see this regularity, since the necessary manipulation 
usually destroys it, but I have on many occasions seen an 
approach to it in carefully compressed sporangia, when the 
membrane was unusually transparent. We know that in 
eight-spored asci the spores are frequently arranged in one or 
two perfectly regular rows with their axes parallel, but I have 
* Quart. Journal Microscop. Science, 1883, p. 276, pi. xxii., fig. 1, d-f. 
f L.c., p. 284, pi. xxii., fig. 16, a-b; fig. 15, d, e. 
{ L.c., p. 499. 
§ Beitr. zur Morph, und Phys. der Pilze, ser. 1, pp. 145-6, pi. 1, 
fig. 14. 
